Field
The present disclosure relates to surgical instruments and in some arrangements to a surgical instrument for moving one part of a surgical implant into an adjacent position or contact with another.
Description of the Related Art
In orthopedic surgery, and particularly in spinal surgery, it is well known to correct an injury, malformation, or other defect using an implanted rod affixed to a body part to be corrected. For example, rod systems have been developed for correcting the positioning of and stabilizing of the spine, and for facilitating fusion at various levels of the spine. In one such system, the rod or elongated implant can be disposed longitudinally along a length of the spine. The rod can be bent, either prior to or during surgery, to correspond to the normal curvature of the spine in the particular region being instrumented, or to such other curvature as the surgeon may deem appropriate to correct the defect. For example, the rod can be bent to form a normal kyphotic curvature for the thoracic region of the spine, or to form a normal lordotic curvature for the lumbar region. The rod can then be attached or engaged to a number of fasteners which have been inserted or implanted into the vertebrae along the segment of the spinal column.
Fasteners are well known in the art and can include all types of bone screws, hooks, bolts, etc. configured to engage the vertebrae. For instance, one such fastener is a laminar hook, configured to engage a lamina of the vertebra. Another prevalent fastener is a spinal screw which can be threaded into a pedicle or other portion of vertebral bone. Examples of spinal screws include monoaxial spinal screws and polyaxial spinal screws.
In some spinal procedures, rods are coupled to two or more fasteners that are fixed to vertebrae, for instance at opposite sides of the spine or spinous processes. The fasteners can be threaded into a portion of several vertebral bodies, such as the pedicles of these vertebrae. The rod can be coupled to the bone screws to provide corrective and stabilizing forces to the spine. Affixing a rod to a fastener generally requires the rod to be in an adjacent position or in contact with the fastener. This may require that the rod and implanted fastener be moved with respect to each other so that the rod occupies space within a channel or other opening in the fastener. The rod can be coupled to the implanted fastener using a set screw, plug or other appropriate closure device. The process of placing a rod within or adjacent to an implanted fastener so that they can be coupled together is termed “reducing” the rod.
Rod reduction is commonly performed by a surgeon using his or her hands and/or rigid tools such as pliers, levers or other instruments able to create the necessary pushing and/or pulling forces on the implanted fastener and rod. Such procedures generally require the surgeon to place the rod directly over the implanted fastener, often intersecting a longitudinal axis of the fastener. Consequently, access to the rod and the fastener directly above the channel in the fastener into which the rod is to be placed can be necessary or at least highly desirable. However, such access can be difficult depending on such factors as the malformation to be corrected and the overall physiology of the patient. Additionally, during minimally invasive surgery, access can be very difficult as a result of the small ports or incisions of such procedures. With use of monoaxial fasteners, the physiology of the patient can require that the screw be placed at an angle such that the surgeon would have difficulty accessing and exerting force in the necessary orientation on the rod and/or the fastener. With polyaxial fasteners, the orientation of an rod-receiving part of the fastener can be varied with respect to the rod and/or the surgeon. Consequently, the surgeon is frequently faced with the task of reducing a rod from an awkward angle.